Process of making beryllium



Patented Apr. 6, 1937 UNITED STATES PATENT PROCESS OF MAKING BERYLLIUMporation of Ohio No Drawing.

5 Claims.

This invention relates to the making of beryllium metal, and an objectthereof is the provision of a novel method of making beryllium in pureform, with greater ease and convenience, and greater economy ofmaterial, than has heretofore been possible.

Other objects and advantages of the invention will be apparent to thoseskilled in the art from the following description thereof.

.In general, the present process comprises treatby dissolving the saltsand leaving behind flake or powdered beryllium. The metal is thencompressed and melted under a suitable flux or in vacuo in accordancewith the methods'now' well known to those skilled in the art. When saltsof other metals are mixed with the beryllium salt they are preferablywater soluble, and either incapable of being reduced by the reducingmetal used or of such a nature that the end products of their reactionwill not alloy with beryllium and'preferably be water soluble. Thereducing metal is preferably so chosen that in the end reaction itproduces a water soluble salt, in which event it is merely necessary toleach the product of the reduction step with water to obtain theberyllium metal where the salts of the other I .etals used are of theaforesaid preferred character.

Among the salts of berylliumthat are suitable for use in this processare the halides, and of these the chloride is preferred. The fluoride isleast suitable because the product of its reaction with the mostdesirable of the metals that can be used to reduceit is such that theberyllium cannot be freed therefrom by leaching. The bromide and iodideare usable, but economically unsatisfactory because of their lowmetallic content and high cost.

. Since the beryllium halides are quite volatile at temperatures only alittle above their melting points, it is not economical to melt themalone except in tightly closed vessels, hence it is preferable todissolve them in other low melting point salts or mixtures of salts. Aspreviously stated, these other salts should preferably be water solubleand either incapable of being acted upon by the metal chosen as areducing agent, or of such a nature that the end products of theirreaction will not alloy with the beryllium and preferably be watersoluble. Many of the simpler salts of the alkali or alkaline earthmetals, such as the chlo- .ture.

Application May 25, 1935, Serial No. 23,519

rides of sodium, potassium, and lithium answer this requirement. Sincethe beryllium halides, and especially beryllium chloride, are quitevolatile even from fused solutions or 'mixtures at higher temperatures,it is desirable to use a fused salt mixture of relatively low meltingpoint in order to prevent the vaporization of the beryllium salt,especially while it is being added to the mix- Lithium chloride, becauseof its low melting point, may be used alone as a diluent for theberyllium salt, but sodium and potassium chlorides are preferably usedin their low melting point eutectic mixture.

Magnesium, in addition to being relatively cheap, abundant andavailable, is altogether the most suitable reducing agent. Its reactionwith the beryllium salts, such as the chloride, dissolved in a fusion ofother salts such as sodium chloride and potassium chloride is very sharpand. definite but comparatively mild and unexplosive. The reaction takesplace over a large range of temperatures starting well below the meltingpoint of magnesium. The products of the reaction are readily watersoluble, permitting the easy separation of the beryllium formed by meansof leaching with' water. The magnesium displaces the sodium andpotassium is limited by the almost explosive violence of the reactionproduced, for which reason they are not well adapted to large scaleproduction. Also the beryllium produced with these metals as well as thealkaline earth metals is preponderantly very fine or fog andconsequently oifers difl'iculties in the later melting steps.

In carrying out the preferred embodiment of the process of the presentinvention an anhydrous beryllium chloride is produced in any well knownmanner, such as the method described in my earlier Patent No. 1,805,567,or it may be produced by methods analogous to those employed inproducing the very similar salts, aluminum chloride and magnesiumchloride, which are now consumed in large quantities in industry. Afusion is then made of approximately equal parts of sodium chloride andpotassium chloride, and this is brought to a temperature only slightlyabove its melting point. To this fusion the beryllium chloride is added.The ratio of beryllium chloride to the sodium and potassium chlorides isnot critical. Fairly satisfactory operation results when the berylliumchloride is any here within the range of 5% to 75% by weight 0 the totalfused salt mixture, but the best yields are obtained'with a berylliumchloride content of about 25%. The greater dilution of the berylliumchloride favors a more complete reaction with the reducing agent, theformation of larger and therefore more useful flakes of beryllium, andalso causes less loss by vaporization of the beryllium chloride. Afterthe beryllium chloride has been added, the resultant mixture has a verymuch lower melting point, which may be well below red heat, depending onthe concentration of beryllium chloride.

The vessel in which the melt is made may be of any convenient materialwhich does not react with the reducing metal as previously stated.Magnesium metal is the preferred reducing agent, and when this is usedthe pot or vessel may be of iron, or ferro-chrome. However, thisintroduces a minute amount of iron as an impurity in the beryllium, andif greater purity is required a vessel or pot made of porcelain or fusedsilica may be used.

After the above melt is completed, the magnesium metal is added,preferably in the form of thin chips, granules, ribbon, or the like. Thereaction takes place at any temperature at which the salt mixture willremain liquid. For example, the eutectic mixture of sodium chloride andberyllium chloride melts at approximately 225 C., and the berylliumchloride reacts with magnesium even at this low temperature. However,the preferred temperature is about or slightly below the melting pointof magnesium. The magnesium is added slowly and the salt bath is stirredconstantly during the reaction. The reaction between the magnesium andthe beryllium chloride takes place evenly and smoothly and withoutviolence. As the magnesium chips enter the bath they are observed toglow and then disappear quickly, while the temperature of the bath risesslowly.

The size of the magnesium particles as added and the stirring of themelt during the reaction are both matters of considerable importance. Iflarge pieces of magnesium are used, they become coated with a layer ofberyllium which seems to hinder further reaction, and leaves a core ofunattacked magnesium. Introducing the magnesi um in fairly small piecesand stirring constantly so as to prevent the beryllium from clinging tothe magnesium and thereby protecting it, obviates this difiiculty andpromotes a complete reaction. It is probably for this reason also thatthe reaction proceeds better at a temperature slighty below the meltingpoint of magnesium since melted magnesium tends to flow together intomasses which expose too little reaction surface.

The amount of magnesium added may be the theoretical calculated weightor slightly less, say 95% of theoretical, to allow for slight loss ofberyllium chloride by vaporization during the melting and reaction. Themagnesium seems to displace the beryllium quantitatively, and at thetemperature employed it shows no tendency to alloy with the beryllium.The end point of the reaction may be observed accurately by the factthat after the reaction is complete any additional particles ofmagnesium added cease to glow. During the melting and reaction a slightdraft may be maintained over the reaction vessel, and directed into acooling chamber. This draws in and condenses the salts lost byvaporization and they can then be recovered and reworked. The entirereaction requires only a comparatively few minutes, and at thecompletion of the reaction the beryllium is present in the melt in theform of loosely coherent sponge. If care is used, this sponge stays atthe bottom of the vessel and the clear supernatant fused salt may bedecanted. The remaining small part of the fused mixture containing theberyllium metal is now permitted to cool, after which it is crushed andleached with water. The products of the reaction and the salts of themelt in this instance, are beryllium, magnesium chloride, sodiumchloride, and potassium chloride. All of these with the exception of theberyllium are water soluble and can be readily separated from theberyllium-by leaching.

The filtering is done first through a screen of about mesh, then througha screen of about 325 mesh, then through filter cloth or filter paper.If any considerable excess of magnesium has been used it is usuallypresent in globules or agglomerates and is retained on the 50 meshscreen. Part of the washing is done with hot water, and the finelydivided excess magnesium, if any, is attacked by the hot water and maybe decanted as hydroxide. In general, however, it is preferable to use aslight deficiency of magnesium, making these precautions unnecessary.The metallic flakes remaining on the 325 mesh screen are all useful formelting into massive ingots, and usually constitute about 75% or more ofthe theoretical metallic content of the beryllium chloride. The veryfine metal that goes through the 325 mesh screen and is retained on thefilter cloth or paper can also be melted into massive ingots, but onlywith considerable loss. It is therefore more economical sometimes toreturn it to the chlorinator and rework it into chloride.

The metal that remains on the 325 mesh screen is preferably compactedinto suitable masses by means of high pressure and then melted either invacuum or under a suitable flux. This results in a loss of about 10%most of which passes into the dross or flux and can be reworked. Withthese various simple recovery steps the yield of massive melted metalcan be made to reach or exceed 95% of the theoretical metalcontent ofthe chloride. The metal so made is exceptionally pure, possessesconsiderable malleability, a property not commonly shown by berylliummade by any of the processes heretofore used, and not definitelyheretofore known to exist, and is especially free from carbon or iron.

The decanted fused salt may be used as a diluent for more berylliumchloride, and another reaction may be carried out, and so on. Duringthis process the salt becomes progressively richer in magnesiumchloride, but this does not affect it adversely. At a suitable period inthe cycle, this anhydrous fused salt mixture containing magnesiumchloride may be poured into an electrolytic cell and electrolyzed tofree the magnesium which may then be used over. The chlorine evolved maylikewise be used over in the chlorinator. Through this cyclical recoveryof the chlorine and magnesium the use of these materials as primaryingredients in the process is reduced to a very small amount and, ineffect, electric power is substituted for them.

The advantages of the process outlined above are made evident by acomparison with the processes of the prior art. .The production ofberyllium has heretofore been attempted by reducing a beryllium halidewith some of the metals of the alkali and alkaline earth groups, butbecause of the volatility of the beryllium halides and their greattendency to oxidize, such a reduction must be carried on in a tightlyclosed strongly built vessel or bomb, and for commercial sizeoperaltions such a scheme is impractical. Also the metal produced ispredominantly fog, and much of its oxide. The use of other fused saltsas a diluent for the beryllium salt makes the closed vessel unnecessaryand permits of a controllable 3 reaction on a large scale atcomparatively low temperature. It also protects the beryllium salts fromoxidation and produces very pure metal. The magnesium replaces theberyllium slowly and quietly, but very completely, permitting practilcally full recovery of the contained beryllium, and in a useful formrather than as fog. A further improvement is brought about by the use ofberyllium chloride, which produces a water soluble end product. Thisrenders the separation of the beryllium easy and emcient.

Magnesium has heretofore been used as a reducing agent for berylliumonly from its fluoride, either to produce magnesium-beryllium alloy, orpure beryllium. This produces the insoluble magnesium fluoride, hencethe beryllium metal cannot be separated by leaching, and the reactionmust therefore be carried on at a temperature above the melting point ofberyllium. The difliculties of finding suitable vessels for holdingfluoride fusions at such temperatures are very great, and the loss ofberyllium fluoride by vaporization is also very serious. The metalproduced must then be re-melted one or more times for purification, withserious losses at each melting. These operative difliculties and lowrecoveries are overcome in the preferred process of this invention.

While the preferred method of practicing the present invention has beenspecifically described, it is to be understood that the same is merelyillustrative of the general method, and that the invention is notlimited thereto, but is obviously capable of many variations, and Iparticularly point out and claim as my invention the following:

1. The process of making substantially pure beryllium metal whichcomprises making a fused mixture of sodium chloride, potassium chlorideand beryllium chloride, and introducing metallic magnesium into thismixture.

2. The process of making beryllium metal which comprises making a fusedmixture of sodium chloride; potassium chloride and beryllium chloride inwhich the beryllium chloride is approximately from flve percent toseventy-five percent of the total mixture with the remaindersubstantially equal parts of sodium chloride and potassium chloride,introducing metallic magnesium into the mixture, leaching the resultantproduct with water, and separating out the beryllium metal.

3. The process of making beryllium metal which comprises making a fusedmixture of sodium chloride, potassium chloride and beryllium chloride,in which the beryllium chloride is approximately twenty-flve percent ofthe total mixture with the remainder substantially equal parts of sodiumchloride and potassium chloride, introducing metallic magnesium into themixture, leaching the resultant product with water, and separating outthe beryllium metal.

4. The process of making beryllium metal which comprises making a fusedmixture of salts one of which is beryllium chloride and the remainder ofwhich is water soluble and does not react appreciably with magnesium,introducing metallic magnesium into the mixture, leaching the resultantproduct with water, and separating out the beryllium metal.

5. The process of making beryllium metal which comprises making a fusedsalt mixture containing beryllium chloride, introducing metallicmagnesium in a form having small crosssection into the mixture while thesame is continuously stirred, leaching the resultant product with water,and separating out the beryllium metal.

HUGH S. COOPER.

